MULTIDIMENSIONAL PAIN INVENTORY PROFILE CLASSIFICATIONS AND PSYCHOPATHOLOGY

MARK A. ETSCHEIDT AND HERBERT G. STEGER

University of Kentucky College of Medicine

BERTON BRAVERMAN

Chicago Institute of Neurosurgery and Neuroresearch, Columbus Hospital

The Multidimensional Pain Inventory (MPI) and the MMPI have been used widely to assess chronic pain patients. This study examined the relationship between patient profile classifications generated by the MPI and psycho- pathology as measured by the MMPI. MPI Dysfunctional and Interper- sonally Distressed means were significantly different than the MPI Adaptive Coper means on scales 4,6,7, and 8 of the MMPI. The Dysfunctional and Adpative Coper means were also significantly different on MMPI scale 2. MMPI profiles for 79% classified as Dysfunctional and 62% classified as Interpersonally Distressed displayed psychopathology as defined by signifi- cant two-point scale elevations. Only 23% of those classified as Adaptive Copers had significant two-point MMPI scale elevations.

This study examined the relationship between patient profile classifications generated by the Multidimensional Pain Inventory (MPI) and indications of psychopathology on the MMPI. The MPI is becoming well recognized as a useful tool in the assessment of chronic pain patients (Etscheidt, 1992; Kerns, Turk, & Rudy, 1985; Tyrer, 1992). The MMPI has a much longer history of use in the evaluation of chronic pain patients (Williams, 1988). Although both are psychological tests used in the evaluation of chronic pain patients, they contrast sharply in how they were developed and the types of con- clusions that can be drawn from them. While the MMPI was developed on a psychiatric population specifically to assess psychopathology, the MPI was developed using chronic pain patients to identify behavioral problems related to their pain.

Although widely used in evaluation of chronic pain patients, acceptance of the MMPI by these patients may be problematic because of its excessive length, psychiatric focus that seems irrelevant to physical problems, and lack of pain- or medical-related content (Bradley, Prokop, Gentry, van der Heide, & Prieto, 1981; Johnson, 1983; Leavitt, 1983; McCreary, 1983; Turner & Romano, 1990). The MPI may be more acceptable to patients because it is briefer (61 items) and has items that are focused on pain and pain-related issues. This factor of patient acceptance has led some pain centers, including the authors', to include the MPI and defer using the MMPI in initial evaluation. Although the MPI provides pain-relevant cognitive and behavioral information, it lacks the MMPI's ability to delineate potential areas of psychopathology, which is useful in screening chronic pain patients. Greater knowledge of the relationship between MPI results and MMPI indicators of psychopathology could be helpful for use of the MPI as a screen- ing instrument to identify those patients who may need further psychological study and/or treatment.

The MPI is a brief, self-administered pain inventory theoretically based upon the cognitive-behavioral perspective of evaluating and managing pain (Kerns et al., 1985).

Correspondence should be addressed to Mark A. Etscheidt, Ph.D., Department of Anesthesiology, Univer- sity of Kentucky Medical Center, 800 Rose Street, Lexington, K Y 40536-0084.

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30 Journal of Clinical Psychology, January 1995, Vol. 51, No. 1

Turk and Rudy (1988) utilized cluster analyses to generate profile classifications for the MPI, including three primary patient profiles now labeled Dysfunctional, Interpersonally Distressed, and Adaptive Coper. Turk and Rudy (1988) confirmed the external validity of these three groups by examining how they score differently on other measures, in- cluding self-monitored pain intensity scores, the McGill Pain Inventory (Melzack & Casey, 1968), the Beck Depression Inventory (Beck, Ward, Mendelson, Mock, & Erbaugh, 1961), the Locke-Wallace Marital Adjustment Scale (Locke & Wallace, 1959), the State scale of the State-Trait Anxiety Inventory (Spielberger, Gorsuch, & Lushene, 1970), and the Multidimensional Health Locus of Control scale (Wallston, Wallston, & De Vellis, 1978).

Assignment to MPI profile classifications is based upon statistical decision-making, which involves assigning each patient to the most probable classification (Rudy, 1989). A complete discussion of how this assignment is made statistically can be found elsewhere (Turk & Rudy, 1987). The Dysfunctional profile includes those patients who have a higher severity of pain and affective distress, who indicate that their pain causes more in- terference in their lives, and who have lower activity levels. The Interpersonally Distressed profile includes patients who indicate that their families and/or significant others are not very supportive of them. The Adaptive Coper profile includes those patients who have lower levels of pain severity, have lower levels of affective distress, have higher levels of life control, have higher levels of daily activity, and report that pain has a lower level of interference in their lives.

The MMPI is a 566-item, true/false personality inventory that has been used fre- quently in the psychological assessment of chronic pain patients. The MMPI was developed by using an empirical keying approach in order to discriminate among pa- tients in various psychiatric diagnostic categories. Over the years, empirical correlates of various profile configurations have been generated (Graham, 1977; Greene, 1980), some of which have been generated specifically for patients with chronic pain (Hart, 1984; Keefe, Block, Williams, & Surwit, 1981; Sternbach, 1974). Although the MMPI has been found to be of questionable benefit in discriminating organic from psychogenic etiology of chronic pain (Cox, Chapman, & Black, 1978; Leavitt, 1985; Leavitt & Katz, 1989), it continues to be recognized for its utility in evaluating psychopathology among patients with chronic pain (Williams, 1988).

The meaning of absolute elevations on MMPI profiles remains a controversial issue in evaluating chronic pain patients. Patients with sufficient organic pathology to account for their pain may display elevated scores on certain MMPI scales because of the effects of pain and chronic illness rather than necessarily reflecting psychopathology. For in- stance, scales 1, 2, and 3 have a number of items that relate to somatic complaints (Franz, Paul, Bautz, Choroba, & Hildebrandt, 1986; Smythe, 1984). These items may be en- dorsed for reasons other than the presence of psychopathology. Thus, a patient may run the risk of being mislabeled as hypochondriacal, depressed, or hysterical because of endorsement of items that relate to actual somatic symptoms or their effects (Prokop, 1986). A similar problem with response pattern on the MMPI has been identified for scale 8 among chronic pain patients (Armentrout, Moore, Parker, Hewett, & Feltz, 1982; Moore, McFall, Kivlahan, & Capestany, 1988). While chronic pain patients with elevated scale 8 scores may show increased pain intensity, sleep disturbance, physical limitations, and psychosocial dysfunction, few will exhibit a significant thought disorder (Armen- trout et al., 1982). When one is interpreting MMPI profiles for chronic pain patients, findings such as these must be taken into consideration.

Currently, no studies are available that examine whether the profile classifications generated by the MPI differ in level of psychopathology reflected in the MMPI. The Dysfunctional and Interpersonally Distressed classifications were derived empirically and identify those patients who report greater cognitive, behavioral, emotional, and/or in- terpersonal difficulties associated with chronic pain. The Adaptive Coper classification

Multidimensional Pain Inventory 31

identifies those patients who are less negatively impacted by their chronic pain. Because the patients classified as Dysfunctional and Interpersonally Distressed present more in- capacitation by their pain condition, one would expect that they would be more likely to have greater and more frequent elevations on the MMPI. This study examined the relationship between psychopathology as measured by the MMPI and profile classifica- tions generated by the MPI for chronic pain patients. Specifically, it was expected that patients classified as Dysfunctional or Interpersonally Distressed would evidence more psychopathology on the MMPI than those classified as Adaptive Copers.

METHOD

Subjects Subjects were 86 chronic pain patients referred for comprehensive psychological

evaluation at an outpatient pain center. This study was reviewed and approved by the institutional Human Investigation Committee.

The mean age was 43.2 years (range 19 to 75 years), 54.7% were females, 62.8% were married, average duration of pain was 5.2 years (range 3 months to 25.5 years), 75.6% were taking at least one of the three commonly prescribed classes of pain medica- tions (i.e., narcotics, nonsteroidal anti-inflammatory drugs, and/or antidepressants), 29.1% were involved in litigation, 60.5% were not working due to their pain, 66.3% reported impaired sleep, 1.2% reported excessive sleep, 43.0% reported weight gain, 12.8% reported weight loss, and 58.1% reported depressed mood. The largest group of patients identified their primary pain site in the lower back (36.0%), followed by the upper shoulder and limbs (25.6%), and the lower limbs (15.1Vo).

Measures The MMPI and the MPI were administered routinely to each patient along with

a structured interview. None of the patients demonstrated invalid or fake-bad profiles based on the criteria of all validity scales less than a T score of 100 (Graham, 1977), and only one met the F minus K raw score difference of minus 11 identified as suggesting a “fake bad” profile (Carson, 1969). In that one case, the profile appeared consistent with the results of the clinical interview and medical findings and was included in the analysis. One of the sample patients did not complete the MMPI, and another did not complete the MPI. These patients were not included in the analyses. MPIs were scored using computer software (Rudy, 1989) that generates scores for the 13 scales and profile classifications.

Analyses Overall between-group significance was tested by MANOVA (Hasse & Ellis, 1987).

Differences among the individual MMPI scales for the three MPI classifications were examined by conducting univariate ANOVAs. Significance was accepted at the .05 prob- ability level after Bonferroni correction.

Chi-square analysis was conducted to evaluate whether the classifications generated by the MPI discriminated between those with and without significant psychological disturbance as estimated by the MMPI. An a priori criterion of two or more clinical scales greater than or equal to a T score of 75 on the MMPI was used for categorizing profiles as reflecting psychopathology. The cut-off was set at a T score of 75 to minimize the risk of false positives due to the fact that many scales contained somatic items and to maximize the likelihood of identifying more severe levels of psychopathology. In ad- dition, two-point codes frequently are used in clinical practice when MMPI profiles are being interpreted, and they are considered diagnostically richer than single scales (Graham, 1977).

32 Journal of Clinical Psychology, January 1995, Vol. 51, No. I

RESULTS

Of the 84 patients who completed both the MMPI and MPI, 63 (75.0%) fell into one of the three primary MPI profile classifications. (See Table 1 .) Of these 63 subjects, those classified as Dysfunctional, Interpersonally Distressed, or Adaptive Copers com- prised 4.4%, 20.6070, and 34.9% of the subsample, respectively. This compares favorably with the distributions among these three profiles cited in previous studies (Rudy, Turk, Zaki, & Curtin, 1989; Turk & Rudy, 1988). The remaining 21 subjects were classified as Hybrid (i.e., 8 were consistent with two or more of the three primary profile classifica- tions), Anomalous (i.e., 8 did not fit any of the three primary profile classifications), or Unanalyzable (i.e., 5 were insufficiently completed by the patient). These 21 profiles were not subjected to statistical analysis. All 8 patients classified as Anomalous were so classified due to fact that they did not complete the MPI items that pertain to a spouse or significant other. The distribution of all 84 patients across the six MPI profile classifica- tions is shown in Table 1.

Table 1 Distribution of MPI Profile Class8cations

Classification n To

Dysfunctional 29 34.5 Interpersonally Distressed Adaptive Coper Hybrid Anomalous

14 16.7 22 26.2

7 8.3

8 9.5

Unanalyzable 4 4.8

The means for each patient profile classification on the MPI (i.e., patients classified as Dysfunctional, Interpersonally Distressed, and Adaptive Coper) were calculated for each of the MMPI clinical scales (i.e., 1, 2,3,4,6,7, 8, and 9). (See Figure 1.) MANOVA revealed a significant main effect among the eight MMPI scales, F(7,420) = 27.40, p < .OO01. Univariate ANOVAs reached significance for scale 2, F(2, 62) = 4.49, p < .015; scale 4, F(2, 62) = 4.61, p < .014; scale 6, F(2,62) = 7.06,~ < .002; scale 7, F(2, 62) = 6.51, p < .003; and scale 8, F(2, 62) = 10.75, p < .Owl. Significance was not reached for scale 1, F(2, 62) = 3.00, p < .057; scale 3, F(2, 62) = 3.12, p < .051; and scale 9, F(2, 62) = 1.12, p < .333. Post-hoc analyses that used the Student-Newman-Kuels Procedure indicated that the Dysfunctional and Interpersonally Distressed means were significantly different (p < .05) than Adaptive Coper means on MMPI scales 4, 6, 7, and 8. In addition, the Dysfunctional mean was significantly different than the Adaptive Coper mean on scale 2 of the MMPI. All these differences were in the direction of the Adaptive Coper means being less than the Dysfunctional and Interpersonally Distressed means.

The number of two-point MMPI code-types for each of the MPI profile classifica- tions then was determined (Table 2). Of those patients classified as Dysfunctional and Interpersonally Distressed, 78.6% and 61.570, respectively, evidenced psychopathology based on the occurrence of a two-point code-type. Only 22.7% of patients classified as Adaptive Copers had significant two-point code-type elevations. Chi-square was statistically significant (p < .0002).

The 1/2, 1/3, and 2/3 MMPI two-point code-types accounted for 56% of all the two-point code-types. The mean number of MMPI scales that reached the criterion of

Multidimensional Pain Inventory 33

"1 MPI PROFILES:

DYSFUNCI'IONAL - INTERPERSONAL *IIIIIII4

FIG. 1. Mean K-corrected T-scores on scales 1-4 and 6-9 of the MMPI for each MPI classification.

Table 2 Distribution of Two-point MMPI Code-types for MPI Profile Classifications

MPI profile classification MMPI code type D ID AC H A U

1/2

1 /3

2/3

2/4

2/7

3 /4

Others Totals

n (070)

3 (10.7)

6 (21.4)

3 (10.7)

1 (3.9)

1 (3.9)

5 (17.9)

22 (78.6)

3 (10.7)

n (To) n (yo)

2 (15.4) 0

I (7.6) 3 (13.6)

1 (7.6) 0

1 (7.6) 0

1 (7.6) 0

0 0

2 (15.4) 2 (9.1)

8 (61.5) 5 (22.7)

0 0

2 (25.0) 1 (12.5)

3 (37.5) 1 (12.5)

0 0

0 0

1 (12.5) 1 (12.5)

0 1 (12.5)

6 (75.0) 4 (50.0)

0

1 (20.0)

0

2 (40.0)

0

0

0

3 (60.0)

Note.-D = Dysfunctional (n = 28), ID = Interpersonally Distressed (n = 13), AC = Adaptive Coper (n '= 22), H = Hybrid (n = 8), A = Anomolous (n = 8), and U = Unanalyzable (n = 5).

34 Journal of Clinical Psychology, January 1995, Vol. 51, No. 1

a MMPI T-score of greater than or equal to 75 was 2.79,2.82, and 1.05 for the Dysfunc- tional, Interpersonally Distressed, and Adaptive Coper classifications, respectively.

DISCUSSION

This study examined the relationship between the primary profile classifications of the MPI and levels of psychopathology as estimated by the MMPI. As expected, chronic pain patients classified as Dysfunctional or Interpersonally Distressed by the MPI evidenced more psychopathology on the MMPI than those classified as Adaptive Copers.

Based upon individual MMPI clinical scales, certain dimensions of psychopathology may differentiate Dysfunctional and Interpersonally Distressed chronic pain sufferers from Adaptive Copers. Dysfunctional and Interpersonally Distressed groups are more likely to exhibit a manipulative, immature self-centeredness and disregard for rules (scale 4); a feeling of getting a raw deal from life along with a distrust of others who are seen as being responsible for one’s problems (scale 6); a proneness to anxiety, worry, and ruminative ideation (scale 7); and an emotional isolation with feelings of being misunderstood and unaccepted by others (scale 8). Dysfunctional chronic pain sufferers are further differentiated from Adaptive Copers by heightened levels of depression (scale 2). Two of the MMPI scales (i.e., scales 1 and 3) that were at one time used to differen- tiate chronic pain patients with and without psychopathology and to predict patient response to treatment (Oostdam & Duivenvoorden, 1983; Strassberg, Reimherr, Ward, Russel, & Cole, 1981; Wiltse & Rocchio, 1975) did not differ among the three primary MPI classifications. Thus, scores on the MMPI 1 or 3 scales appear to add little in- cremental information to understanding differences among the three primary MPI pro- file classifications.

It was interesting to note that the MMPI profiles for the Dysfunctional and Inter- personally Distressed MPI classifications have some similarities with MMPI profiles cited by Sternbach (1974) and Hart (1984). The Dysfunctional group had primary elevations on scales 1, 2, and 3 of the MMPI, which has been characterized as an indication of excessive dwelling on somatic symptoms or hypochondriasis. The Interpersonally Distressed group had primary elevations on many of the clinical scales of the MMPI (i.e., scales 1,2, 3,4,7, 8), in a manner that has been characterized as showing general emotional disturbance. Patients with Interpersonally Distressed profiles, therefore, had more MMPI indications of psychopathology than those classified as either Dysfunc- tional or Adaptive Coper.

The number of elevations on the MMPI suggests that patients with Interpersonally Distressed profiles experience more psychological disturbance than those classified as Dysfunctional or Adaptive Coper. However, statistical comparison of the MMPI pro- files of the different MPI classifications suggests that the Dysfunctional profile may be more indicative of psychopathology for the following reasons: None of the MMPI scales differed between the Dysfunctional and Interpersonally Distressed groups; the Dysfunc- tional and Interpersonally Distressed groups were significantly higher than the Adap- tive Coper group on MMPI scales 4, 6, 7, and 8; and only the Dysfunctional group was significantly higher than the Adaptive Coper group on the Depression Scale.

The Adaptive Coper group had low absolute levels on all the MMPI scales when compared to the Dysfunctional and Interpersonally Distressed classifications. In addi- tion, the Adaptive Copers had proportionally fewer two-point MMPI code types and had no code types that involved depression (scale 2). Consistent with the implication of their description as “adaptive copers,” it is clear from the present results that patients with Adaptive Coper profiles have the least difficulty of the three groups with psychologi- cal disturbance. One would expect that the Adaptive Coper patient might benefit from behavioral and psychological interventions aimed at pain-related issues (e. g., pain coping techniques, behavioral adaptation, etc.), whereas the Dysfunctional and Interpersonally

Multidimensional Pain Inventory 35

Distressed patients might require more psychological intervention aimed at broader issues (e.g., suffering, disability, emotional distress, depression, interpersonal conflict, etc.) in addition to more traditional pain-focused treatment.

This study did not investigate the level of psychopathology among the Hybrid, Anomalous, and Unanalyzable MPI classifications because of the small number of sub- jects in each classification. The Hybrid classification is not a homogeneous group in that these profiles are a mixture of Dysfunctional, Interpersonally Distressed, and/or Adaptive Coper characteristics, which renders the MMPI findings ambiguous at best for this classification. Given the high incidence of two-point MMPI code-types for the Hybrid classification, further research on psychopathology for this subgroup is warranted.

The MPI was designed to evaluate the patient for psychological factors that con- tribute to the patient’s chronic pain condition (e.g., emotional, cognitive, interpersonal, behavioral). As such, the MPI provides specific information that can be useful in devis- ing cognitive-behavioral treatment for chronic pain and in evaluating treatment progress. The findings of this study suggest that emotional, cognitive, interpersonal, or behavioral dysfunction, as assessed with the MPI, are related to psychopathology as measured by the MMPI. Practical advantages to using the MPI vs. the MMPI include ease of ad- ministration and scoring, time savings on the patient’s part, and lessened adverse patient reactivity because the MPI addresses pain-related issues. Some practitioners may elect to utilize MPI results as part of the criteria in determining the need for more extensive psychological investigation with the MMPI or other psychodiagnostic procedures.

For those who presently utilize the MPI, the findings suggest that those patients classified as Dysfunctional or Interpersonally Distressed are more likely to have difficulty with psychopathology than those classified as Adaptive Copers. The results of the MPI can provide information useful for identifying pain patients who may require more in- tensive psychological services as part of their chronic pain treatment.

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